SRVO-062: BZAL alarm (pulse coder battery zero)

What it means

The battery backing up the encoders' absolute position data is dead or disconnected - the robot has lost track of where its axes are. The fix is a sequence, not a step: battery, pulse reset, power cycle, then deal with SRVO-075 and re-master. Skipping steps is why this alarm has a reputation.

Common causes

Ranked by what technicians most often find, most likely first.

1. Backup batteries in the robot-base battery box depleted or removed.
2. Battery-to-encoder cable inside the robot disconnected or grounded - the prime suspect when BZAL appears right after a fresh battery install.
3. Failed motor/pulse coder (last suspect).

How to fix it

1. Replace the batteries in the robot base battery box.
2. Perform the PULSE RESET operation (per the manual's Pulsecoder Alarm Recovery section), then cycle power.
3. Expect SRVO-075 'Pulse not established' on the next power-up - that's normal; jog each affected axis slightly and reset per its procedure.
4. Re-master: quick mastering if a reference position was previously set, full mastering otherwise.
5. If BZAL returns after new batteries, stop and check the internal battery cable before replacing anything else.
6. Verify positions carefully before production - mastering errors move real steel to wrong places.

Related codes

• SRVO-075Pulse not established
• SRVO-063RCAL alarm (rotation counter abnormal)
• SRVO-066CSAL alarm (pulse coder checksum)
• SRVO-067OHAL2 alarm (pulse coder overheat)
• SRVO-068DTERR alarm (pulse coder no response)
• SRVO-069CRCERR alarm (pulse coder data corrupt)
• SRVO-070STBERR alarm (pulse coder framing error)
• SRVO-071SPHAL alarm (feedback speed excess)